Damper in a washing machine and fabricating method of the same

Abstract

A damper for a washing machine includes: a cylinder; a piston body having one end inserted into the cylinder; a first friction member interposed in a contact surface between the piston body and the cylinder; an extension bar extended from an inserted portion of the piston body, the extension bar having a circumferential stopper at the extended portion; a friction ring formed between the circumferential stopper and the first friction member; and a second friction member formed on an outer circumferential surface of the friction ring to contact with an inner surface of the cylinder.

1. A damper for a washing machine, comprising:
 a cylinder; 
 a piston body having one end inserted into the cylinder; 
 a first friction member interposed in a contact surface between the piston body and the cylinder; 
 an extension bar inserted into and extended from said one end of the piston body further into the cylinder, the extension bar having a circumferential stopper at the extended portion; 
 a friction ring formed between the circumferential stopper and the first friction member; and 
 a second friction member formed on an outer circumferential surface of the friction ring to contact with an inner surface of the cylinder. 
 
   
   
     2. The damper for the washing machine according to  claim 1 , wherein the extension bar has a diameter smaller than the piston body. 
   
   
     3. The damper for the washing machine according to  claim 1 , wherein the extension is provided as a separate part and fixedly inserted into the piston body. 
   
   
     4. The damper for the washing machine according to  claim 1 , further comprising a friction ring rotation preventing means for preventing a rotation of the friction ring. 
   
   
     5. The damper for the washing machine according to  claim 1 , further comprising an elastic member formed on at least an inner surface of the friction ring. 
   
   
     6. The damper for the washing machine according to  claim 1 , further comprising a reinforcement rib formed on one side of the friction ring to reinforce a strength of the friction ring. 
   
   
     7. The damper for the washing machine according to  claim 1 , wherein the extension bar and the piston body are formed as one body. 
   
   
     8. The damper for the washing machine according to  claim 1 , wherein the extension bar and the piston body are molded as one body. 
   
   
     9. The damper for the washing machine according to  claim 1 , wherein the circumferential stopper is a separate part and connected to the extension bar. 
   
   
     10. The damper for the washing machine according to  claim 1 , wherein the friction member is an elastic and porous plastic coated with a lubricant. 
   
   
     11. A damper for a washing machine, comprising:
 a cylinder; 
 a piston body having one end inserted into the cylinder; 
 a first friction member interposed between the piston body and the cylinder; 
 an extension bar inserted into and extended from said one end of the piston body further into the cylinder, the extension bar including a circumferential stopper expandedly formed at a predetermined position of the extended portion; 
 a friction ring formed between the circumferential stopper and the piston body and operated by the circumferential stopper and the piston body; and 
 a second friction member interposed in a contact portion between the friction ring and the cylinder. 
 
   
   
     12. The damper for the washing machine according to  claim 11 , further comprising a hook protrusion formed protrudedly on an outer circumference of the friction ring to support a formation position of the second friction member. 
   
   
     13. The damper for the washing machine according to  claim 11 , further comprising a cooling fin formed on an outer circumference of the piston body. 
   
   
     14. The damper for the washing machine according to  claim 11 , wherein first friction member and/or the second friction member are/is formed by spacing apart two or more members. 
   
   
     15. The damper for the washing machine according to  claim 11 , wherein the piston body and the circumferential stopper contact with both ends of the friction ring. 
   
   
     16. The damper for the washing machine according to  claim 11 , further comprising an elastic member surrounding an inner circumferential surface and outer surface of the friction ring, the elastic member being formed as one body. 
   
   
     17. A damper for a washing machine, comprising:
 a cylinder; 
 a piston body having one end portion inserted into the cylinder and a hollow central portion; 
 a first friction member interposed between the piston body and the cylinder; 
 an extension bar having one end portion insertedly fixed to the central portion of the piston body and the other end portion extended from the piston body, the extension bar including a circumferential stopper expandedly formed at the extended end portion; 
 a friction ring formed between the circumferential stopper and the piston body and operated by the circumferential stopper and the piston body; and 
 a second friction member interposed in a contact portion between the friction ring and the cylinder. 
 
   
   
     18. The damper for the washing machine according to  claim 17 , comprising:
 an elastically deformable opening and or a hook protrusion, the elastically deformable opening being formed at one end portion of the extension bar and being elastically deformable; and 
 an insertion groove formed on the piston body and caught by the hook protrusion. 
 
   
   
     19. A damper for a washing machine, comprising:
 a cylinder; 
 a piston body having one end portion inserted into the cylinder; 
 a first friction member interposed between the piston body and the cylinder; 
 an extension bar inserted into and extended from said one end of the piston body further into the cylinder; 
 a friction ring formed on an outer side spaced apart from the extension bar; 
 a friction ring rotation preventing means for preventing a rotation of the friction ring; and 
 a second friction member formed on an outer circumferential surface of the friction ring to contact with an inner surface of the cylinder. 
 
   
   
     20. The damper for the washing machine according to  claim 19 , wherein the friction ring rotation preventing means includes a non-circular inner circumferential surface of the cylinder and a non-circular outer circumferential surface of the friction ring. 
   
   
     21. The damper for the washing machine according to  claim 19 , wherein the friction ring rotation preventing means includes a non-circular inner circumferential surface of the friction ring and a non-circular outer circumferential surface of the extension bar. 
   
   
     22. The damper for the washing machine according to  claim 19 , wherein the friction ring rotation preventing means includes an elliptical inner circumferential surface of the cylinder and an outer circumferential surface of the friction ring having a shape corresponding to the inner circumferential surface of the cylinder. 
   
   
     23. The damper for the washing machine according to  claim 19 , wherein the friction ring rotation preventing means includes an outer circumferential surface of the extension bar and an inner circumferential surface of the friction ring having a shape corresponding to the outer circumferential surface. 
   
   
     24. The damper for the washing machine according to  claim 19 , wherein the friction ring rotation preventing means includes a spline formed on an inner circumferential surface of the cylinder contacting with the friction ring and/or an outer circumferential surface of the extension bar. 
   
   
     25. The damper for the washing machine according to  claim 19 , wherein the friction ring rotation preventing means includes a fixing key formed on an inner circumferential surface of the cylinder contacting with the friction ring and/or an outer circumferential surface of the extension bar. 
   
   
     26. The damper for the washing machine according to  claim 19 , wherein the friction ring rotation preventing means includes a serration formed on an inner circumferential surface of the cylinder contacting with the friction ring and/or an outer circumferential surface of the extension bar. 
   
   
     27. A damper for a washing machine, comprising:
 a cylinder; 
 a piston body having one end portion inserted into the cylinder; 
 a first friction member interposed in a contact surface between the piston body and the cylinder; 
 an extension bar inserted into and extended from said one end of the piston body further into the cylinder, the extension bar including a circumferential stopper formed on the extended portion; 
 a friction ring formed between the circumferential stopper and the first friction member, the friction ring including a reinforcement rib protrudedly formed on an inner circumferential surface; and 
 a second friction member formed on an outer circumferential surface of the friction ring to contact with an inner surface of the cylinder. 
 
   
   
     28. The damper for the washing machine according to  claim 27 , wherein the piston body and the circumferential stopper contact with both end portions of the friction ring during an operation of the damper to thereby make the friction ring operate. 
   
   
     29. The damper for the washing machine according to  claim 27 , further comprising an elastic member formed on an insertion end portion of the piston body and/or an inner surface of the circumferential stopper. 
   
   
     30. The damper for the washing machine according to  claim 27 , wherein the piston body and the circumferential stopper contact with both end portions of the reinforcement rib to thereby make the friction ring operate. 
   
   
     31. The damper for the washing machine according to  claim 27 , further comprising an elastic member formed on both sides of the reinforcement rib. 
   
   
     32. A damper for a washing machine, comprising:
 a cylinder; 
 a piston body having one end portion inserted into the cylinder, and an extension bar extended from said one end portion of the piston body inserted in the cylinder and having a diameter smaller than the piston body, the extension body being inserted inside of the piston body and the extension bar being an integral body; 
 a first friction member interposed in a contact surface between the piston body and the cylinder; 
 a friction ring formed between the extension bar and the first friction member; and 
 a second friction member formed on an outer circumferential surface of the friction ring and contacting with an inner surface of the cylinder. 
 
   
   
     33. The damper for the washing machine according to  claim 32 , wherein the piston body and the extension bar are formed by an injection molding. 
   
   
     34. The damper for the washing machine according to  claim 32 , further comprising a circumferential stopper connected to an end portion of the extension bar as a separate part. 
   
   
     35. The damper for the washing machine according to  claim 32 , further comprising a circumferential stopper formed on an end portion of the extension bar, the circumferential stopper being inserted into an inner/outer surfaces of the extension bar. 
   
   
     36. The damper for the washing machine according to  claim 32 , further comprising a circumferential stopper connected to an end portion of the extension bar as a separate part to contact with the friction ring. 
   
   
     37. The damper for the washing machine according to  claim 32 , further comprising a circumferential stopper connected to an end portion of the extension bar, the circumferential stopper having a diameter larger than the extension bar. 
   
   
     38. The damper for the washing machine according to  claim 32 , further comprising a circumferential stopper fused on an end portion of the extension bar. 
   
   
     39. A method for forming a damper having a cylinder and a piston extension bar for a washing machine, comprising the steps of:
 inserting a friction ring into an outer side of, and spaced apart from, the piston extension bar of the damper; 
 arranging a circumferential stopper in one end of the piston extension bar to fix the circumferential stopper to the piston extension bar; and 
 inserting the piston extension bar into the cylinder. 
 
   
   
     40. The method according to  claim 39 , further comprising injecting the extension bar as one body together with a piston body. 
   
   
     41. The method according to  claim 39 , further comprising fusing the circumferential stopper to the extension bar. 
   
   
     42. The method according to  claim 39 , further comprising forming the extension bar as one body together with a piston body and forming a stepped portion at a portion in which the extension bar and the piston body is are connected to each other. 
   
   
     43. The method according to  claim 39 , wherein the extension bar has a diameter smaller than the diameter of the piston body.